Transmitting system



J. A. WILLQUGHBY TRANSMITTING SYSTEM Oct. 17 1933.

Filed Dec, 22, 1928 4 Sheets-Sheet l Oct. 17, 1933. J. A. WILLOUGHBY I 1,930,863

TRANSMITTING SYSTEM Filed Dec. 22. 1928 4 Sheets-Sheet 2 M 1933- J. A. WILLOUGHBY 1,930,863

TRANSMITTING SYSTEM Filed Dec. 22. 1928 4 Sheets-:Sheet s Oct. 17, 1933. J. A. WILLOUGHBY TRANSMITTING SYSTEM Filed Dec. 22, 1928 4 Sheets-Sheet 4 Patented Oct 17, 1933 p I 1,930,868 TRANSMITTING SYSTEM. John A'.. Wil1oughby, Cambridge, Mass.

Application. December 22, 1928- Serial No. 327,975

' 12 Claims.

My invention relates to transmitting systems in general and more specifically to transmitting systems for the transmissionof continuous wave energy.

An object of my invention istoiprovide a transmitting system whereby'the' energy receivedfrom such a system is not afiected by" fading.

Another object of my invention is to provide a thermionic tube transmitter whereby the energy is radiated alternately from twoindependent radiating systems.

Still another object of my invention is to' provide a thermionic tube transmitter whereby the energy is simultaneously radiated from two individual radiatingsystems followed by radiation fromthe one, radiation from the two and fol-' lowed by the radiationfrom theother' in a predetermined successive order. A

A further object of my invention is to provide a transmitting system employing thermionc tubes whereby the propagated waves travel in' different 7 paths to the receiving antenna and" atdifierent phase angles. I 3 Other and further objects of my invention re- 5' side in the circuit arrangements employedin the transmitting systenr of my invention, aibetter understanding of which can be hadfrom the specification following and from the accompanying drawings wherein, Figures I, 2", 3" aud t show modifications of the transmitting systems of my invention.

The phenomena of fading of the received energy has been attributed'to terrestrial magnetism and to many other causes. Fading of thereceived energy is commonlyiexperienced and is believed to' be related toatmospheric and barometric conditions as it is more orless pronounced during certain periods. The facts. seem toindi cate that the propagated waves are neutralized by other sources of energy or the conditions of the atmosphere for the conduction of the W'qWe energy are changed; Fading is;experienced from stations transmitting from a; given locality while energy from otherstations, having substanti'ally the same location is unaffected. Fading of "the received signaling energy seems tolikewise affect both horizontally and verticallypolarized waves; In the-transmitting system'of my inventionfad ing of the received signaling energy is greatly reduced.

Fig. l of the accompanying drawings-shows one form of the transmitting system ofmy invention. Like reference characters are employed i'n all the drawings thermionic tube 1' employed in an oscillatory circuit arrangement; the

(CI. 250I7) ihput'circuit comprisinga piezo electric element and the output circuit an inductance having frequency characteristics corresponding approximately' to the frequencycharacteristics of the H piezo electric" element or "a frequency multiple 69 thereof. The energy from the output circuit of thermionic tube .1 is associated with'theinput circuit of thermionic tube 2.. Thermionic tube 2 amplifies the energy from the output circuit of thermionic tube 1. The amplified. energy is transferred from the output circuit of thermionic tube. 2 to the input circuit of thermionic tube 3. Thermionic tube 3 further amplifies the energy received from. thermionic tube 2. Thermionic tubes 1', 2 and 3 are herein illustrated as of the three electrode type however tubeshaving', four or more electrodes may be employed. The anode circuits of thermionic tubes 1,2 and 3 are energized from source 21 through suitable resistance units for reducing. the applied potential. The

control electrodes of thermionic tubes 1, 2 and 3 are supplied with a source of biasing potential from source 12; The cathode circuits are energizedby individual batteries however it is obvious that the source of energy maybe alternating cur- 89? rent,. a motorgenerator' or other suitable means. The output circuit of thermionic tube 3 includes inductance 4. The high frequency signaling energy is transferred from inductance 4 to the con- A trol electrodes 5 andfi of thermionic tubes '7 and 8; Thermionic' tubes '7 and 8 are shown having a common cathode connection with thermionic tubes 1, 2and 3'. Thermionic tubes 7' and. 8 are illustrated as of the foul-electrode type, however it is obvious that any tube may be employed having more than three electrodes. The cathodes of thermibnic tubes land 8 are shown energized by individual batteries and itis likewise obvious that a. common source of any suitable potential may be employed their stead. The anodes I7 and 18 and shielding anode electrodes 19 and 20 of thermionic tubes '7? and 8 respectively are energized from source 21 byway of' choke coils' 23', and 23a. Thermionic'tubes'l and 8 are connected in a balanced'ampli'fier' circuit arrangement the amplified energy from which is associated with output circuits 1'3 and Pi respectively. Out-- put circuits 1'3 and 14- are associated with space radiatingsystems'15, 15a an'd16, lfia respectivefys V A-- source of directcurrent control electrodebiasm5 ing potential is suppliedcontrol electrodes 5 and. 6 from source 12 throughan 'intermediatetapj oftransformer secondary winding I1; through the res'pectivesections of this winding on each side of this intermediate point and through conductors 11a and 11b and high frequency choke coils 22 and -22a, respectively. One connection from source 12 leads to the common cathode circuit. A source of alternating potential 9 is electrically associated with the primarywinding of transformer 10.

The operation of the transmitting system of my invention schematically illustrated in Fig. 1-is as'folllowsz" The amplified. high frequency energy from the output circuit 4 of thermionic tube 3 is transferred to control electrodes 5 and 6 of thermionic tubes '7 and 8 respectively. 1 A.

supply of biasing potential from source 12 is of the proper value to ,causefboth tubes? and-8' to amplify the energy from output. circuitfi and transfer the same to output circuits'l Hand to radiating systems 15, 15a'and 16,- .16a. Source of alternating potential 9 is associated with transformer 10 which latter is connected in the 7 control electrode circuits of thermionic tubes 7 source 12 'thereis applied a voltage which is.

always of the}same sense] and value; i There is also applied in-both circuits, through winding sections 11a11j and 11 -11b the, alternating voltage of source 9 and theinstantaneous values of this voltage at a giveninstant are, applied in the same sensein both of these winding sections. Atany instant the efiective yoltage acting in of the voltage appliedin thislcircuit by source 12 and the voltage. appliedin this circuit by source 9, and correspondingly for circuit-- 1'2,:1-1?-1;1b- 6 9-12.; j ,5 "Assume? an instant whenjsources applies to the windings ofj;11', a'poten'tial whichiin itself would make terminal 11''; positive withrespect to' the intermediate tap, and which" itself;

would make thejintermediate tap positive with respect to terminal 11b; Then circuit12- 11 11q.5712, source .Shlpplie's a voltage which opposes the .voltage applied by'source 12' and the resultant instantaneous'v tage in this circuit is the difference oflthetwd applied Qvoltages and less thanfifsourcee were removed. Atthe same ii 1'stant,, in circuit, 12 11741125 5- 812 source 9 applies-a .voltagewhich assists the voltage applied'by source 1 2, and the resultant instantaneous voltage; in, this :latter circuit has a value which is the sumof the twdappl-ied volt-- ages and greater invalue thanif source 9, were removed; 1 [That is, {when the potential across winding 11, 1 1a due to source 9, Bedding tov the potential from source 12 the potentialacross winding 11,. 11b due to source 2,- i subtracting from the potentialirom source 12 Thiscauses an increase; in ,the. control electrode biasing potentialsupplied control electrode 5 and; a reduction in the value of potential ,supplied control electrodefi. The characteristics of thermionic tubes! and 8 may bes uc ih that the nor.- mal potentialsupplied by. other sources such as 12, to;.the control electrodes, neglecting source 9 is of the proper yaluetcpausethese tubes to function as amplifiers. An increase in value of negative potential may cause a blocking of the tube or cause the tube to fail to amplify. For the purpose of explanation suppose that tubes .of the above mentioned characteristics correspond to thermionic tubes '7 and 8. Let us further assume an instant when the polarity of connection lladue tosource 9, is positive in respect to nodal pointv or intermediate tap 11, and the polarity of 1112 due to source 9 is negative with respect to tap 11. This potential, due to source 9, would subtract from the negative po of connection 11b would be negative in respect to node 11.

The potential 1l11b, due to source 9, would add to the potentialfrom source 12 and reduce the amplification or totally block the operation of thermionic tube 8. No energy would be transferred to output circuit 14oz" to radiating circuit 16, 16a. At'the end of the next quarter cycle the potential supplied controi elecplied with a corresponding potential and would amplify the energy from output circuit 4. Both thermionic tubes 7 and 8 are now amplifying the energy from source e where, during the preceding quarter cycle, thermionic tube 7 was functioning as an amplifier and thermionic tube 8 was inoperative because of the'high negative potential impressed upon control electrode 6. At the end of the following quarter cycle, due to; source 9, connector 1111 would have a negative potential in respect to nodal connection 11. The polarity in this instance would cause. the potential from source 9 to add to the potential from source 12 and a hi h negative potential would be impressed upon control electrode ,5 of: thermionic tube'l. This potential would block the operation or reduce the amplification of thermionic tube 7. Since connector 11a is 'negativein respect to connector 11, conhector l lbwou'ld be positive in respect to connector 11. Keeping in mind that connector' 1i iseommon with the cathode circuits of both thermionictubes' 7 and 8,-the polarity of the potential from .source 9 would, during this quarter cycle' neutralize or reduce the negative potentialimpressed upon control electrode'fi of thermionicYtube-SQ Therefore thermionic tube 8' wouldamplify the energy from. output circuit 4andtransferfthe same to output circuit 14 and radiatir'i'gsystem 16, 16a. At the end of the next io' iiarter cycle-the potential from source Qis-Zero' and. the potential impressed upon control-electrodesfi and. 6 of thermionic tubes 7 and 8 respectively,is substantially/that from source 12. "Both thermionic tubes 7 and 3 now operate as amplifiers and circuits 13, 14, 15, 1551,16 and i amplifier while at the 'same time the operation j of. thermionic tube; 8,:is' prevented gbecause ofthe high; negative potential impressed-,uponfits 0011-,

trol electrode 6. It is obviousthat the conditions described-for the'final instants of. each quarter cycle will obtain to some extent, throughout that quarter cycle. ,Choke, coils22 and 22ahave the proper frequency. characteristics toj'offer a-substantially low. impedance to the potential from SUUICQS'Q 3,116.12 butto ofierwa high impedance to, the highfrequency energyfrom output circuit 4.. Radiatingsystems .15, a, and;16,':-16a ,may be placedin difierentj'planesfl'whereby the propagated waves are horizontally .01 vertically polarized in respect tothe earths surface:

Theumodeyof operation which .has been described assumes a magnitude coiljconstant, grid biasing potential .from direct current. source 12 which is approximatelythe. normal. operating grid biasing potential for maximum 'efiiciency.

and. which is-appreciably less ,than-.the'.direct current potentialwhich alone would blockboth tubes. The system 1 can be operated in another manner by applying a negativecontinuous po- .tentialirom direct current source 12 whichalone is of magnitude somewhat greater than that.

requiredto block tubes 7 and 8. Underthese CD11,- ditions, with no other; applied electromotive force asirom source 9,].n6ithertube- Thor, 8 will deliver energy; 11f now "an alternating potential from source '9fis applied, of peak valuesuflicient to decrease at the instants of peak the 'continf ,uous negative bia's' to'a value below the blocking point, oneoithe-tubes'l or 8 will deliver energy.

while thisalternating current positive peak value stant with this arrangement inwhich both-tubes. are simultaneously delivering energy, in which. respect the 'operationis different from that preexists. One tube alone will deliver energy. then the other tube alone-will deliver energy,,then the.

firsttube alonewill deliver energy,- 'et c. Unless the yaluesof direct'current and alternating cur; rent potentials, are very closely adjusted there will beintervening periodswhenneither tube de livers energy. In'any case, there wililbefno in-.

viously described.

. Fig. '2 or the accompanying drawings shows-"another form of the transmitting system orf my invention. :Source o-= energy 25 corresponds to er on c-tu s 2 a a d theien er-fimm. e tru cu ema ca ly:ill st a ed. in

Fig. l o f the accompanying drawings. Source of high fr ue en g 251 ca se jz .en tsi controlelectrodes 5 and fi oi thermionic itubesfl n 8 see i he ii e circu t re ne gized by our Wh h m rqons t Qib es a motor-generator as shown, or any, suitable means; The output circuitsof thermionic; tubes '2 and 8 include inductances, 13 and l liand radiating systems lS andlfi -resp ectively. Radi-J ating systeins '15 com.prise"thecommonly known doublets or other suitable arrange- 1 mentsQand maybe positior edin horizontal and vertical planes whereby the propagated waves are horizontally and vertically "polarized; in 1 respect to the earths surface. Thermionicj tube 26 comprise's a suitable oscillatory-circuit arrangement including input circuit 2'7- and output. circuit '28. Tneelectrical centeijof inductance 28a mayjbe connected to ground potential if'necessaryto'ese tablish the required node. Thisis accomplished,

in the accompanying circuit arrangement by con-.

.necting. contact member ll-zto ground potential by means of .a suitablejcapacityg. Thelcapa'city pathisQsuitableior alternating current While the :direct; ?or. continuous current path 1 includes sistance to the passagethereofwhile oiiering a '11b OfFig. land, havea potential difierence in substantially -:hi'gh resistancejto the high fre- "quency energy from source25 Source of potential 21a, supplies the necessary energy to the anode circuit of thermionic. tube '26; The e'nergyfrom v output circuit 28 is transferred to control elec trodes 5 and. 6 of. thermionic tubes 7 .and..8 by

means of connectors 11 a and 11b.- Connectors 11a and 11b. correspond to "connectors 11a. and

respect. to contact member 11. Connectors 11a. and'llb alternate'through different polarities in respect ro the "polarity of icontact member .11. The impressed poter'itialblocks the operation of thermionic tube 7 while allowing thermionic tube 8 tol'amplify, followed by the unlolocking of ther-,

"mionic'tube '7 anda reductionin the'amplification of thermionic tube 8;followe'd by the block; ing of tube 8 and the unblockinglof tube 7; The

cycle of operation is substantially the same as that 10 0 10f the circuit arrangement shownv in Fig. l=ofthe accompanying drawings; 7 V

."Figs, j3rand .4 "show twolother forms of the transmitting system oi my invention. Fig. Bis a schematic circuitarrangementshowing source of high fre quency'energy 25 associated'with control electrodes 5' and-6 of thermionic tubes 7 and 8 respectively.- The anode circuits of thermionic tubes 7 ands: are energized from source21. Qutput circuits 13 andli associatedwith thermionic tubes '7 and8 respectivelyrare associated with transmission lines 38, 38a. Transmission lines 38, 38a are-also associated with radiating cir cults 32, ,20and 33, 31,1espectively. Radiating circuits 32;'30 and 33, 31Lcomprisecoil=antennas 1 5 and suitable"coupling inductancesl Coil an tenn'as30"and 31fmay be placed at right angles to'eachg other; .It is well known that a coil .an1- tenna when-excited radiates energy in afigure 8 characteristic. However, when two coil antennas 12o placed at'right angles to each other are excited alternately veryrapidlwsuch as the superimposing of' 'commutating' lvoltages upon the control electrodes of-an oscillator. or amplifier tube, the

above mentioned figure'B characteristic"will now' 5 produce .airadiatedfield 0f energy of two figure 8s' at rightangles'eachtothe other resulting in a non-.-directional wave. -;Ini Fig. 3 thesource of commutating -.'-'voltagescomprises generator, 9

which is 'shunt'edqbya suitable resistance. The

electrical center or'a point near the electrical center of the resistance isjconnected to the com.- mon' cathode connection of thermionic tubes 7 andB; 'lhe commutating voltagesare impressed r upon control- ,e lectrode'sjfi and. 6 of thermionic- 5 tubes 7; and 8 Jay. way. of chokelcoils 2V2 anaaza respectively. Cholze coils 22 and-2Zcfhaye'the proper'freq'uency. characteristics to. ofier' allow impedance to the. commutatingvoltages from source 9 and: at the same timeoiiera high; rm- I40 pedance to the passage of :high'frequency energy. I from source 25. By employing acircuit arrange;

mer t of -.this type-it is possible to transmit energy from on'ecoil antenna, followed-by transmission from the first coil-antenna and a second coil an- 14 5 .tenna, followed by, transmission from the second, w again transmitted from theatwo and continuingin this manner in 3/5 repeating 1.successive order.

Fig. 4 of the;accompanying drawings.shows a modification of. thelcircuitarrans s hematically illustrated inrFig..3. In this circuit arrange: ment the referenceicharacters correspond to those employed in :the: foregoing; illustrations. Coil antennas 30 and 31 are associated with output circuits 13 a d-v14 of thermionic tubesil-and 18 'byjmeans of transmission lines 38-and 38arespectively. Controlpelectrodes i and 6 ofithermionic tubes '7 and 8 respectively, are, supplied with commutating voltages from. source 9.- Coilv antennas. and 31 are associated with inductances'32, '34jand 33,l35"respective1y.; InductancesB' and 35 are associated with radiating systems 15' and lfi respectively.:.fCoil antennas 30 and 31' may beplaced .irr'any desired position including the ninety: degreev relation, forlpro-- ducing the'composite figure8 effect. "The transmission from coil, antennas 3O and 31 wouldlbe substantially as, from coil antennas30and 31 of Fig. 3 ifnthey were placed illxSllChLDOSlfiOllS} Radiating systems15 and .-l6 mayscomprise suit therefore {cause Ya' non'edirectionall wave 'to be propagated while antennas 1 5 and l6'would cause the propagation ofjverticallyjand horizontally polarized waves. The'meceptiodfof signaling energy from'ithe aforementioned ,arrangementis substantially free :from fading zeffect. ,Antennas 15 and; 15 may be. positioned: at any desired por tion of transmission lines '38 and 38a; respectively andcomprise any suitable type of space" radio radiating system.';:

- In the: foregoing; specification and-:in the accompanying drawings I have referred 'toxand --illustratedicertainitypes ofthermionic tubes. '-It is 1 obvious that thermionic tubes, having ,fourior moreelectrodes-may beiemployed; Batteries are "shown'in the accompanying drawings: as are also generators as. sources". of electrical energy. ,It ;1s

obvious that anyj suitable source of electrical 7 any suitable frequencyq; n I llrealize-that;manymodificationsofthe-transe scopefof the'appended 'claim'sic eurrent control, electrode biasing potential, a

source of alternatingenergy of lower frequency energy may be: employed: Thefcom'mutating potential may comprise "an suitable means and of mitting system .of myiinventioncanbe had with out departing fromnthe spirit of my invention and it is to 'be understoodf'thatamy invention shall not be limited tontheiioregoing specification or to "the accompanying drawings but only by;the

i1-'.-In'- a'transmitting systerhfof the-type 'employing' thermionic tubesf'adap'ted to-ainplify a source" of high frequency: energy the combina tion offa pluralityjof thermionicitjibes symmetri V cally arranged in two groups; a 1 source ofdirect than. said f rst finentioned' source; means 'for exciting the'control electrodes of l said thermionic tubes from said last mentionedjsource said means firstconditioningfone'iof said tubes to amplify I v saidfhi'gh frequencyenerg y' to'the exclusion of "other" of said, tubes" -for a given time interval,

said means next] conditioning: said plurality of tubes vto' jointly amplify 11 said high frequency energy for a succeeding time; interval and said 'meansnext conditioning another of saidtubes 7 to exclusively"amplify-said energy forthe next succeeding time ir'iterv'al" in 'the order named; the

a What I claim as new. and'de'sire'to secure Letters"; Patent off the" United States is as "fol- ,1ows;,

meeogses directional electrical relationship between the' load remainingunreversed.

i ZJA transmitting:system comprising in combination a source-of high frequency electrical energy, a plurality of thermionic tube amplifys ing means connected with said source, a "plurality of individual radiatin v systems connected to the output circuits of said amplifying'means,

outputof each 'of said groups of tubes and the one of said radiating systems propagating horizontallypolariz'ed waves and'another, of said radiatin'g'systems' propagatingvertically polarized waves,- asourceof direct current connected with the control electrodes of each of said thermionic tubes hand a source of alternating of each of said thermionictubes and opintervaL-j nextconditioning one of said tubes to amplify saidenerg'y independently fora given time interval and then conditioning another of said tubes to amplify said energy for a succeeding timeintervalasubstantially in the successive order set 'forth V 3.1A transmitting system comprising in combinationa source'of high frequency electrical 'energyfa plurality of thermionic'tube amplifying means connected with said source, a -plural-. ity of individual radiating systems 7 connected with said amplifying means, one of said radiat-- ing systemsbeing positioned in-a horizontal plane 90. c'urrent' -connected with the control electrodes erative to bias each of said tubes for con -g .ditioning each of said tubesto amplify said energy; simultaneouslyfora predetermined time and another of said 1 radiating systems beingpositioned in a vertical plane in respect to the earthssurface, a source of direct current control electrode biasing potential, and" a source of alternating current connected with the control electrodes of said} thermionic tubes; for fconditioning all o'f 's'aidftubes to amplifysaidenergy for a'given time interval, some of said' tubes-to L ampIifysaid energy for a succeeding time inter-- val and another of said tubes to"a'mp li fy said energy for the next succeeding time interval sub stantiallylinthe successive order above named. v 4. Atransrnittingsystem' comprising in combinatibna' source "of high frequency electrical" .energy, a plurality of thermionic tube amplifying means connected with said source, a pluralityof individual radiating systems associated with said amplifying means, said radiating system'skeomprisingi'directional coil antennas spaciallyfpositioned substantially fat right angles each" tothe 'othen 'asource 'or" "direct current controlelectrodebiasing potential, and a source of alternating" current connected with the control electrodes of said'thermionic tubes for conditioning vall of said tubes to; amplify said energy for a-g'iven time interval, one of said tubes to-amplify'said energy for a succeeding time interval and another 'of-fsaid tubes; to amplify I saidenergy for the-next succeeding; time interval 'substantially in the successive order above named. 5'. A transmitting system comprising'in combination a source o f-high frequency electrical energy, a plurality of thermionic tube amplifying means associated with said source, a plurality of individual radiating systems respectively connected with said amplifying means,

said radiating systems comprising directional coil antennas spaciallypositioned substantially at right angles each to the other, individual positioned antennas, V and a source of alternating current connected with the control electrodes of horizonta11y" positioned and'individual vertically (Illin succession.

said thermionic tubes for conditi'omng: an of said tubes to amplify saidgenergy for a-given time interval,- one of -'said tubes to amplify I saidenergy fora succeeding time interval and 'another of said tubes to amplify said energy for: the next succeedingtime interval substantially in the-sue cessive order-above named. T

6. In -a transmitting system; asource of highfrequency energy, two electron tubes "having cathode, control grid -andpIate electrodes, balanced input andoutput circuits therefor, a source of direct current grid biasing potential'of valu'e not great enough to block said tubes, individual antennas respectively iii-electrical relation with the o'utputcircuits' of each-of said tubes, a transformerhaving the terminals of its secondaryrespectively connected to the control grids of said;

tubes and having an'intermediate tap connected through said source of biasing potential to the cathodes of said tubes, th'e primary of said trans former being supplied with; alternating current of a frequency less than that'of said source of high frequency energy and of maximumfvalue suflicient to'apply a'total' biasing voltage sufficient to'block one or both of said tubes for a predetermined time interval in succession, 'where-= by one of said tubes alone delivers energy to its corresponding antenna for a given time interval,both of said tubes deliver energy to their corresponding antennas for a succeeding time'interval, and the other of said tubes delivers energy to its corresponding antenna for the next succeeding'time interval, in succession.

a 7. In a transmitting system, a source of high frequency energy, a piezo electric crystal element,

circuits connecting said piezo electric crystal element to said source and adapted to cause said piezo electric crystal element to 'maintain constant the frequency of said source, two electron tubes having cathode, control grid and plate electrodes, balanced input and output circuits therefor adapted to cause saiditubes tolamplify' said energy supplied by said source, a source of direct current grid biasing potential of value not great enoughto block said tubes, individual antennas respectively in electrical relation with the output circuits of each of said tubes/a transformer having the terminals of its secondary respectively connected to the control grids'of said tubes and having an intermediate tap connected through said source ofbiasing potential to the cathodes of said tubes, the primary of said transformer being supplied with alternating current of a frequency less than that of said source of high frequency energy and of maximum value sufficient to applyja total biasing voltage sufficient to block one of said tubes at a time, whereby one of said tubes alone delivers energy to its corresponding antenna for a given time interval, 7

both tubes deliver energy to their corresponding antennas for a succeeding time interval, and the other tube delivers energy to its corresponding antenna for the next succeeding time interval,

8. In a transmitting systempa source of high frequency energy, electron tubes having cathode,

control grid, shielding grid, and plate electrodes, balanced input and output circuits therefor, a source of direct current'grid biasing potential I of value not great enough to blockisaid tubes,

individual antennas respectively in electrical re- 1 lation with the output circuits of each of said 7 groups of tubes, a transformer having the ter- ,minals of its secondary respectively connected to the control grids of each group of said'tubes and having an intermediate tap connected through said source or biasing potentialto the'cathjodes of said-tubes; the primary "of said transformer being supplied with alternating currentora frequency less than that of said source of high frequency energyfand of maximum value suffi'cient: to apply atotal biasing voltage sufficient to block one potential of value not "great enough" to block said" tubes, individual antennasrespectively connected in electrical relation with the output circuits'of' each of saidlgroups of tubes, said antennas haying markedly "different radiation characteristics, atransformer having the terminals of it's sec-drie -ary respectively connected to the control grids of each group of said tubes and having an intermediate tap connected through said source of biasing potential to the cathodes of said tubes,

the primary of said transformer being supplied with alternating current of a'frequency less than that of said source of high frequency energy and of maximum value sufficient to apply a total biasing voltage sufficient to block one group of said tubes at a time, whereby one group of said tubes alone delivers energy to its corresponding antenna for a predetermined time interval, both groups of .tubes deliver energy to their corresponding antennas for the succeeding time interval, and

l the other group of tubes delivers energy to its corresponding antenna for the next succeeding time interval, in succession.

10. In a transmitting system, a source of high frequency energy, two symmetrical groups of electron tubes having cathode, control grid, and plate electrodes, balanced input and output circuits therefor, a source of direct current grid biasing potential of value not great enough to alone block said tubes, individual antennas respectively connected in electrical relationship with the output circuits of each group of said tubes, said antennas having, markedly different radiation characteristics, a transformer having the terminals of its secondary respectively connected to the control grids of each group of said tubes and having an intermediate tap connected throughsaid source of biasing potential to the cathodes of said tubes, the primary of said transformer being supplied with alternating current of a frequency less than that of said source of high frequency energy and of maximum valuegreat enough to increase the total biasing voltages over short periods to a value suincientto block one tube at a time, whereby one group of said tubes alone delivers energy to its corresponding antenna for a predetermined time interval, next both groups of said tubes'deliver energy to said antennas for the succeeding time interval, and the other group of tubes alone de- [livers energy to its corresponding antenna for the next succeeding time interval, in succession.

11. In a transmitting system, a source of high frequency energy, two symmetrical groups of electron tubes having cathode, control grid and plate electrodes, balanced input and output circuits therefor, a source of direct current grid biasingzpotential ofvalue not great enough to block said tubes, individual antennas respectively inoutput of each of said; groups of tubes and the radiation of its corresponding antenna remaining unreversed, whereby one group of said tubes alone delivers energy to its corresponding antenna for a' predetermined ;time interval,1 both groups of tubes deliver. energy to their corresponding antennas; for asucc'eeding time interval, and the other group of tubes delivers energy to its cor- .r'espondingantenna for the next succeeding time interval, succession.

12. Atransmitting systemcompris'ing a high f requencyoscillator, a,pair,of' branch circuits, a

power amplifier connected in eachof said branch circuits and hav ngthe input thereof supplied with energy from said oscillator, a radiating system of differing transmission characteristics connected with the output of each of said'power amplifiers, a direct current source connected with the control circuits of said power amplifiers for preconditioning the operation thereof, an alternating current supply source superimposed uponthe control'circuits of said power amplifiers for automatically effectingthe transfer of energy from said oscillator exclusively to one of said radiating systems of a particular transmission characteristic for a predetermined time interval, next effecting the transfer of energy simultaneously to both of said radiating systems forthe next succeeding time interval, and next effecting the transfer of energy exclusively from the other of Y said radiating systems of different transmission characteristic for the next succeeding time interval JOHN A. WILLOUGHBY. 

